Are you aware of the psychological aspect of how bettors choose between over or under? For starters, over/under bets is a type of sports betting where bettors try to predict whether a combined number of score of both teams is over or under a predetermined value. It is observed that beginners tend to bet on the over side. Why? Because over means excitement.
Over means the bettor is anticipating a lot of action and this is how bookmakers get to them. If you have been watching and betting for a long time however, you may be able to objective and exercise restraint and not be overly excited over a match and only bet on the under side. Anyway, under is not always the correct answer as it really depends on the match, the teams, the gameplay and many other factors but most beginners end up getting too excited and betting mostly on over without proper analysation.
Before placing a bet on a team, one must do a lot of research about that team. How that team has played in the past, how is their consistent performance, etc. These things determine our psychology. We often get very excited about our favorite teams, and at that time we place big bets on them. But we cannot win the rest. The reason for this is that we forget to check how strong the team is playing against that team due to being too excited. So in the case of gambling, we have to accept that it is not possible to win all bets. So there should be no overconfidence in any bet. Gambling winning should be left to luck.